staging: comedi: cb_pcidas: convert driver to use the comedi_8254 module

This driver uses two 8254 timers to generate the pacer clocks. One for analog
input acquisition and one for analog output data conversion. Convert it to use
the comedi_8254 module to provide support for the 8254 timers.

Use the comedi_device 'pacer' member for the 8254 timer used for analog input.
This data is freed automatically by the core during the detach of the driver.

Store the data for the 8254 timer used for analog output in the private data.
This data needs to be freed by the driver when it is detached.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>